50i or 50p

[jparnold]

I am sure this has been covered before however I am at present on a trip with my brand new Panasonic HC-X920M and just discoverd that after 2 weeks I have been recording at (format) 1080/50i and that I could have chosen 1080/50i. This is the first time I have used a HD camera after using a SD DV tape camera in the past for some years.
I believe that 50i is interlaced and that 50p is progressive HOWEVER which is BEST to use for highest quality and especially ease of editing?
Also within the format choices for 50i I can choose 'normal quality', 'high quality', or 'maximum quality', Apart from the obvious how does each vary - is it only the compression (such as with jpeg stills) which varies?

Thanks

[Ken Berry]

50p gives you the highest quality output, and maximum would probably use the camera's highest compression rate which I understand is AVCHD 2.0 at 28 Mbps. Editing would be much the same for both 50i and 50p -- though remember to enable 50p editing in X6 under Settings when you film in 50p.

You may be aware from general discussion on this forum that AVCHD is very demanding of computer resources. Yours should be able to manage. But if you find that preview etc is stuttery, use SmartProxy.

[jparnold]

Thanks Ken,
I can always rely on a prompt informative reply from you.

Regarding being resource hungry I was intending to upgrade to an i5 around 3.2Ghz so that should be even better.

I am wondering then if I should start recording in 50p for the remainder of the trip as there is a logical 'break' in my trip at present and therefore would probably make a 'movie' of the past 2 weeks separate from the remainder.
Does your information remain the same should I intend to create Blu-Ray disks from my video? I am not sure as yet how I will 'store' my rendered movies for viewing and possible sharing with friends. I still have to learn about these options.

My camera allows me to choose between 4 'grades' of quality for 50i but only ONE 'grade' for 50p. Not sure this is normal and also if 50p (one quality) is still better than 50i set at highest quality.

As I haven't recorded in 'full HD before' I haven't been followng any posts or threads on this matter yet and so have a lt to learn and catch up.

Thanks again

[Ken Berry]

Well you hit the nail on the head with your question about Blu-Ray discs. At the moment, the international standard for such discs only includes 50/60p if the frame size is no more than 1280 X 720. In other words to burn a Blu-Ray disc using 1920 X 1080 (or even 1440 X 1080) video, you can only burn interleaved video i.e. 1080i, or in other words, 1080p is down-converted to 1080i. When this might change is anyone's guess.

But my recommendation would still be to use 1080 at full 50p (though you can probably also select 25p???). My own experience has been that down-rendering 50p to 50i is easy and, to my ageing eyes at least, entails no noticeable loss in quality.

[jparnold]

Thanks again Ken,
I will now use 50p - Not sure but don't think my Panansonic 920 has 25p.
It is interesting that Blu-Ray isn't full 1980x1020.

[Ken Berry]

Well it certainly isn't "1980x1020" as you put it... though I realise that was just a typo on your part. It is of course 1920 x 1080 but not fully "p". Hopefully, though, the time must be coming soon when the international standard will be changed to include it...

[erdna]

Sorry to come in a bit late. I have been working on unwilling computers...I am using 50p for quite some time now (Panasonic TM700 and Sony GW55 more recently). Works OK. You can create a fullHD BD out of a 1920x1080p video in VS. Of course, when doing so, the video is being re-interlaced to get 1080i. The only thing is (as I reported ealier) that you end uo with a 25p temporal resolution. This is because VS uses only one (50p) frame out of two. It then creates a 1080i stream by extracting the even and uneven lines out of the same (50p) frame. Only "in camera" conversion and Edius (much more expensive than VS) do the re-interlacing job right.

[jparnold]

Sorry Ken Yes it was a typo - your eyes getting older (as you say) my fingers getting older

And thanks erdna for your inut. I remember some of what you both have been explaining but some months ago when I was thinking of upgrading my GS400 to my 920. I then waited some months until I could purchase and then went overseas without doing much 'testing' and had forgotten.
Thanks again.

One last question - does X4 or X6 take advantage of all the 'threads' of the Intel i5 and i7 CPU's?

[Ken Berry]

Regarding your last question, the general consensus is that it is supposed to take advantage, but in practice does not, or at least not very much even after tweaking. See for example a discussion of this which is very recent: http://forum.corel.com/EN/viewtopic.php ... 21#p276021

[jparnold]

FYI
Just found the following info regarding recording times for the X920M using 32GB SD memory card
1080/50p 2hr 40min
1080/50i highest quality 3hr
50p has a higher (28mbps) data transfer rate that 50i highest quality

Strangely the published recording times for the 32Gb inbuilt memory is around twice that for same size (32Gb) SD memory card - that doesn't seem right!

[jparnold]

Am home and ready to edit my AVCHD video.

I note that when setting 'project properties' and using AVCHD I can choose 1920x1080 50i or 1280 x 720 50p.
I have 'Googled' BluRay and AVCHD and noted that with BluRay progressive scan video can go up to 1920×1080 pixel resolution at 24 frames per second.
I note from a previous reply that it is best to record at 1080p which I am now doing.

So what should I be using during editing?

It seems that if I use AVCHD 50p I will loose some resolution ie AVCHD 1920 x 1080 50i to 1280 x 720 50p

Does it matter if I edit at 1920 x 1080i if the input video is recorded at 50p?

Or should my project properties be BluRay 1920 x 1080p?

I have attempted to sort this out using Google but it is so complex.

[Ken Berry]

Well, again it really depends on what you intend to do with the video. If you intend making Blu-Ray discs, then you could probably stick with 1920 x 1080i -- though my experience using 1080p originals and "downgrading" them to 1080i to burn to disc did not reveal any problems that I could see.

But if you intend to make high quality HD footage which you will play back more directly on your HDTV i.e. via a USB stick or external hard drive plugged either directly into your HDTV or into a Blu-Ray player connected via HDMI to your HDTV, then I would stick to doing everything in 1080p at the full 50/60 full frames per second.

Mind you, you might be surprised at how good the quality of 1280 x 720p (at 50/60 fps) can be. As I said somewhere, it was for a very long time the HD TV broadcast standard in many parts of the world and probably still is in some parts.